This invention is directed to an improved method of manufacturing antenna isolators of the type used with television receivers.
Antennas and other video signal sources are now being isolated from A.C. line voltages which may appear at the tuner of a television receiver. One of the most convenient and effective forms of isolators for this purpose is described in U.S. application Ser. No. 282,824, filed July 13, 1981 now U.S. Pat. No. 4,399,419. A portion of one such isolator is shown in FIG. 1, to which reference is now made.
The illustrated portion 10 of the isolator includes a cylindrical ferrite bead 12 having a central aperture 12a, a cylindrical dielectric element 14 having a central aperture 14a, and another cylindrical dielectric element 16 having a central aperture 16a. The ferrite bead 12 is normally sandwiched between the dielectric elements 14 and 16 to form a unitary structure.
The dielectric element 14 has a conductive metal coating on its outer circumference 18 and another conductive metal coating on its inner circumference 20. The end face 22 of the element 14 is free of any metal coating and is typically bonded to an immediately adjacent end face of the ferrite bead 12 by an epoxy adhesive.
The dielectric element 16 is constructed similarly to the element 14 and is bonded to the end face 24 of the ferrite bead. The resulting unitary assembly may then be housed within a metal connector with the metal coatings on the outer circumferences of the elements 14, 16 soldered to the inner surface of the connector to form concentric capacitors.
The problems addressed by this invention relate to the manner of plating the dielectric elements 14 and 16 and the manner in which the isolator is assembled within its connector. Previously, the elements 14, 16 have initially had their entire surface areas coated with metal. Their end faces, such as end face 22, were then lapped to remove therefrom the previously plated metal. Although the resulting capacitors operated satisfactorily, lapping tends to be time consuming and, therefore, an expensive operation for high volume production.
Proper mounting of the isolator within its connector includes soldering the metallized outer circumferences of the dielectric elements to an adjacent inner surface of the connector. This assembly step has proven to require considerable care since the surfaces to be soldered are difficult to access. In practice, one of the limiting factors on the isolator's yield has been the ability to quickly and properly effect this step of the assembly.
Accordingly, it is a general object of the invention to provide an improved method of fabricating an isolator of the type described above.
It is a more specific object of the invention to provide an improved method of depositing a metal coating on the inner and outer circumferences of the isolator's dielectric elements.
It is another object of the invention to provide an improved method of joining the isolator to its connector housing.